The mechanical interactions between cell membranes and the proteins imbedded in them may have important effects on the activity of the proteins. In the case of the post-synaptic receptor proteins of the central nervous system, alteration of this interaction by general anesthetic agents may explain the mechanism of general anesthesia. These membranes and proteins are not at present available for investigation; however, the chrolinergic receptor-membrane complex isolated from the electroplaque organ of electric fish such as Torpedo or Electrophorous species is available as a model. We will attempt to detect changes in the molecular volume of these receptors consequent upon binding of cholinergic agonists. We will also investigate the possible modification of these changes by the presence of general anesthetics. This will provide information useful in evaluating the "membrane fluidizing" hypothesis of anesthesia. We will study the change in volume of the receptors when a general anesthetic alone is introduced into the system; this will shed light on the possibility of conformational changes in the proteins produced by general anesthesia. We plan to use a Michelson interferometer to detect the molecular volume changes. We will use these data to evaluate the possibility of various types of mechanical interactions between the membrane and its imbedded proteins, and the relationship of these interactions to the mechanism of general anesthesia.